Study On The Memristive And Memcapacitive Memory Performance Of Organic-Inorganic Halide Perovskites

As the human society enters the information age,various intelligent electronic devices are gradually popularized into people's daily lives.The amount of data generated in every day,and the total amount of global data will show an exponential growth.Massive data has brought the demand on ultra-large-capacity storage devices.With the development of the times,silicon-based semiconductor devices have gradually reached physical theoretical limits in terms of size and performance.Therefore,it is important to explore the new generation of Non-Volatile Memory(NVM).Memristor and Memcapacitor are new types of the memory in which the material impedance(or capacitance)can undergo reversible transformation between high resistance state(HRS)/high capacitance state(HCS)and low resistance state(LRS)/low capacitance state(LCS)under the action of external electric field.Compared to Flash,DRAM and SRAM,Memristor/Memcapacitor has the same characteristics as low power consumption,small size,fast read-write speed.And they are very prospective and competitive in the next generation of the Non-Volatile Memory.Especially Memcapacitor has many advantages which Memristor doesn't have,such as different storage mechanism,elimination of the problem of sneak path currents,lower ON/OFF voltage,lower power consumption.It shows that most of the switching behavior of memristor/memcapacitor is closely related to the ion migration behavior in materials.And now the main memristor/memcapacitor was made by inorganic metal oxides,new two-dimensional semiconductor materials,organic small molecules,polymers.However,the improvement of multi-level storage and performance in memristor and memcapacitor was hindered by many problems,such as low-level storage in memristor and unrealized memcapacitor,due to the limitation of the ion migration speed in materials.And then it is urgent to develop new types of materials to move these obstaclesOrganic-inorganic hybrid perovskite materials(OIHPS)are widely used in solar cells,optoelectronic devices and other fields.However,there is a current-voltage hysteresis effect in the OIHPS based optoelectronic devices,which can be used to fabricate memristors.The memresistive switching is usually accompanied by the memcapacitive switching under AC electric field which OIHPS may be the excellent candidate materials to study.In this paper,the memristor and memcapacitor made by OIHPS will be studied to improve the density and performance of memory devices:from the binary to quantemary of Memresistor,and then to the better quantemary performance of Memcapacitor.The work is as follows:(1)CsPbBr3 quantum dots have excellent photoeleetric properties and excellent stability.CsPbBr3 QDs were fabricated into memristor with the SiO2/ITO/PMMA/CsPbBr3 QDs/PMMA structure,and it was found that they have the Flash storage performance(2)MAPbBr3 polycrystalline film was fabricated into memristor with quaternary information storage in an ON/OFF resistance ratio of 102-103.The device has good separation of the ON/OFF resistance and can be operated repeatedly.At the same time,our resistance states have the excellent characteristics of long retention time(>104 seconds)and good endurance(>104 pulses).In addition,the performance of the MASnBr3-based flexible memory device is still good even after being distorted 1000 times.Finally,the mechanism of memristor is discussed in detail.(3)Through the in-depth comparison on the memristor performance MAPbBr3 in the form of single crystal and polycrystalline stature,it is found that the perovskite MAPbBr3 polycrystalline film is more distinct than that of the single crystal film.The carrier mainly transmits through the grain boundary.This discovery will promote the development of many fields of OIHPs,such as solar photovoltaic cell,memristor with multi-level information storage.(4)A new type of memory device,which is made of organic-inorganic metal halide perovskite(represented by MASnBr3),has a C-V hysteresis loop and a Q-V pinch hysteresis loop,and is strictly accord with the definition of ideal Memcapacitor.The ITO/MASnBr3/Au memory device,which has a distribution range of 0 to 169 pF in capacitance,can be modulated into at least four stable capacitance states.It has a long retention time(at least 104s)and good endurance(at least 104 pulses).The mechanism of memcapacitive behavior is discussed in detail at the end.It was revealed the fundamental difference between Memristor and Memcapacitor,and confirmed that MASnBr3-based memory has independent memcapacitive behavior.